The present invention relates generally to compressors and more particularly to reciprocating refrigeration compressors of the hermetically sealed type.
Hermetic refrigeration compressors are utilized in a wide variety of residential and commercial applications. In all of these applications the compressors are required to provide reliable operation over an extended period of time with little or no maintenance and as economically as possible. In order to provide reliable, economical, maintenance free operation for long periods of time, it is highly desirable to design a compressor which has as few parts as possible and which may be easily manufactured and assembled and is as compact as possible.
The present invention provides a compressor of the reciprocating piston hermetically sealed type which offers a unique approach to accomplishing the above often conflicting objectives. In the present invention, the compressor assembly and stator are each independently and directly supported by the outer shell thereby eliminating the need for separate support members which also aids in simplifying assembly thereof. Also, the compressor assembly is designed to utilize the outer shell to retain the head and valve assembly in assembled relationship with the compressor body thereby almost entirely eliminating the need for separate fasteners.
A unique, simple and straightforward cam drive arrangement is also provided which offers significant improvement in the operating efficiency of the compressor by providing a longer time period for exhausting compressed refrigerant from the cylinder as compared with compressors employing substantially more complicated scotch yoke drive arrangements. Additionally, the cam drive mechanism is able to provide this increased discharge time with a cam member which acts as a combination wrist pin and connecting rod and which is received within an opening in the piston.
Thus, the maximum size of the compressor may be reduced to be no greater than the diameter of the stator, thereby enabling the assembly to be placed in a relatively small circular shell. Also, the use of a one piece piston and connecting rod further reduces the number of parts required as well as the associated assembly time.
An improved discharge muffler is also incorporated in the present compressor which has an inlet directly connected to the compressor housing thereby eliminating the need for separate tubing to conduct discharge gas thereto from the compression chamber. The discharge muffler also forms a part of the outer shell and because the compressor is rigidly supported by the shell, it is possible to provide a direct outlet connection for supplying compressed refrigerant to other components of the refrigeration system.
A unique method of assembling the present invention is also disclosed wherein the compressor and stator are assembled in separate shell sections which are then accurately positioned and secured together in a manner which substantially avoids any distortion thereof due to heating from welding. The method of assembly also includes a method of selecting a head gasket of suitable thickness to insure positive sealing of the head and valve assembly to the compressor body upon press fitting thereof into the shell.
In order to assure positive and sufficient lubrication of the present invention, one embodiment incorporates a rotary valve which selectively places the upper end of an axially extending oil passage in communication with a substantially closed crankcase so as to create a pressure differential within the oil passage to aid in flow of lubricant therethrough. In another embodiment, the oil passage is in continuous communication with the crankcase which is vented to the interior of the shell through pressure responsive valved openings. Thus, the cyclic low pressures resulting from reciprocal movement of the compressor operate to assist flow of oil through the axially extending passage.
Thus, the present invention provides a remarkably unique and novel compressor which offers the advantages of low cost assembly and improved reliability due to the substantial reduction in the number of parts required, an extremely compact design and efficiencies of operation not previously attainable in compressors of comparable size.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.